diff --git a/frappe/core/doctype/doctype/test_doctype.py b/frappe/core/doctype/doctype/test_doctype.py
index dc6d14b451..bc9a411ebd 100644
--- a/frappe/core/doctype/doctype/test_doctype.py
+++ b/frappe/core/doctype/doctype/test_doctype.py
@@ -1,6 +1,9 @@
 # -*- coding: utf-8 -*-
 # Copyright (c) 2015, Frappe Technologies Pvt. Ltd. and Contributors
 # License: MIT. See LICENSE
+from typing import Dict, List, Optional
+import unittest
+
 import frappe
 import unittest
 from frappe.core.doctype.doctype.doctype import (UniqueFieldnameError,
@@ -507,7 +510,7 @@ class TestDocType(unittest.TestCase):
 
 	def test_autoincremented_doctype_transition(self):
 		frappe.delete_doc("testy_autoinc_dt")
-		dt = new_doctype("testy_autoinc_dt", autoincremented=True).insert(ignore_permissions=True)
+		dt = new_doctype("testy_autoinc_dt", autoname="autoincrement").insert(ignore_permissions=True)
 		dt.autoname = "hash"
 
 		try:
@@ -521,25 +524,31 @@ class TestDocType(unittest.TestCase):
 			dt.delete(ignore_permissions=True)
 
 
-def new_doctype(name, unique=0, depends_on='', fields=None, autoincremented=False):
-	doc = frappe.get_doc({
-		"doctype": "DocType",
-		"module": "Core",
-		"custom": 1,
-		"fields": [{
-			"label": "Some Field",
-			"fieldname": "some_fieldname",
-			"fieldtype": "Data",
-			"unique": unique,
-			"depends_on": depends_on,
-		}],
-		"permissions": [{
-			"role": "System Manager",
-			"read": 1,
-		}],
-		"name": name,
-		"autoname": "autoincrement" if autoincremented else ""
-	})
+def new_doctype(name, unique: bool = False, depends_on: str = "", fields: Optional[List[Dict]] = None, **kwargs):
+	doc = frappe.get_doc(
+		{
+			"doctype": "DocType",
+			"module": "Core",
+			"custom": 1,
+			"fields": [
+				{
+					"label": "Some Field",
+					"fieldname": "some_fieldname",
+					"fieldtype": "Data",
+					"unique": unique,
+					"depends_on": depends_on,
+				}
+			],
+			"permissions": [
+				{
+					"role": "System Manager",
+					"read": 1,
+				}
+			],
+			"name": name,
+			**kwargs,
+		}
+	)
 
 	if fields:
 		for f in fields:
diff --git a/frappe/model/document.py b/frappe/model/document.py
index 15e9c28d83..1d47957f67 100644
--- a/frappe/model/document.py
+++ b/frappe/model/document.py
@@ -3,6 +3,8 @@
 import hashlib
 import json
 import time
+from typing import List
+
 from werkzeug.exceptions import NotFound
 
 import frappe
@@ -21,8 +23,6 @@ from frappe.core.doctype.server_script.server_script_utils import run_server_scr
 from frappe.utils.data import get_absolute_url
 
 
-# once_only validation
-# methods
 
 def get_doc(*args, **kwargs):
 	"""returns a frappe.model.Document object.
@@ -179,7 +179,7 @@ class Document(BaseDocument):
 		if not self.has_permission(permtype):
 			self.raise_no_permission_to(permlevel or permtype)
 
-	def has_permission(self, permtype="read", verbose=False):
+	def has_permission(self, permtype="read", verbose=False) -> bool:
 		"""Call `frappe.has_permission` if `self.flags.ignore_permissions`
 		is not set.
 
@@ -195,8 +195,15 @@ class Document(BaseDocument):
 		frappe.flags.error_message = _('Insufficient Permission for {0}').format(self.doctype)
 		raise frappe.PermissionError
 
-	def insert(self, ignore_permissions=None, ignore_links=None, ignore_if_duplicate=False,
-				ignore_mandatory=None, set_name=None, set_child_names=True):
+	def insert(
+		self,
+		ignore_permissions=None,
+		ignore_links=None,
+		ignore_if_duplicate=False,
+		ignore_mandatory=None,
+		set_name=None,
+		set_child_names=True,
+	) -> "Document":
 		"""Insert the document in the database (as a new document).
 		This will check for user permissions and execute `before_insert`,
 		`validate`, `on_update`, `after_insert` methods if they are written.
@@ -276,7 +283,7 @@ class Document(BaseDocument):
 		"""Wrapper for _save"""
 		return self._save(*args, **kwargs)
 
-	def _save(self, ignore_permissions=None, ignore_version=None):
+	def _save(self, ignore_permissions=None, ignore_version=None) -> "Document":
 		"""Save the current document in the database in the **DocType**'s table or
 		`tabSingles` (for single types).
 
@@ -498,8 +505,7 @@ class Document(BaseDocument):
 		self._save_passwords()
 		self.validate_workflow()
 
-		children = self.get_all_children()
-		for d in children:
+		for d in self.get_all_children():
 			d._validate_data_fields()
 			d._validate_selects()
 			d._validate_non_negative()
@@ -840,7 +846,7 @@ class Document(BaseDocument):
 			frappe.throw(_("Cannot link cancelled document: {0}").format(msg),
 				frappe.CancelledLinkError)
 
-	def get_all_children(self, parenttype=None):
+	def get_all_children(self, parenttype=None) -> List["Document"]:
 		"""Returns all children documents from **Table** type fields in a list."""
 
 		children = []
@@ -1399,6 +1405,3 @@ def execute_action(doctype, name, action, **kwargs):
 
 		doc.add_comment('Comment', _('Action Failed') + '<br><br>' + msg)
 		doc.notify_update()
-
-
-